
Written by a model from the transcript; not yet reviewed.
This episode covers the creation and capabilities of Claude Code and the newly shipped Opus 5 model, featuring a discussion on how modern AI agents can run for extended periods, rewrite large codebases, and maintain software autonomously. The guest and host explain why traditional development practices like over-specifying system prompts and rigid system design are obsolete, arguing instead for an empirical approach where developers "unhobble" models by deleting system prompts and letting agents verify their own work. Listeners will gain practical insights into leveraging dynamic workflows, test-time compute, and automated routines that spawn thousands of agents to handle tasks ranging from dead code removal to complete language migrations.
Hosts welcome Boris Cherny and discuss the recent release of Opus 5 and its performance gains.
Boris explains Opus 5’s ability to run long tasks, avoid prompt injection, and its improved alignment.
Discussion of how Claude Code deletes and rebuilds its system prompt with each model release to match new behavior.
Boris outlines the iterative ablation process of removing and re‑adding prompt lines to find the minimal effective harness.
Discussion on whether coding is solved, what remains challenging, and the skills that differentiate top builders.
The concept of unhobbling Claude and exploiting product overhang to unlock hidden model capabilities is introduced.
Boris shares real‑world use cases, such as codebase rewriting and creative tasks like drawing with OpenCV.
Explanation of dynamic workflows, loops, and routines that launch thousands of agents for complex tasks.
Claude runs daily routines to clean code, write tests, and unify abstractions across multiple apps.
Boris shares his personal learning journey and advises students to focus on practical, product‑oriented skills.
Hosts wrap up, announce a special offer for attendees, and encourage building long‑running agentic projects.
Opus 5 Long-Horizon Autonomyinsight
Opus 5 introduces the capability to run autonomously for days, weeks, or even months at a time without requiring external scaffolding.
Eliminating Prompt Injectiondata
By combining three years of alignment research, a traffic prompt injection classifier based on mechanistic interpretability, and an auto mode classifier, Opus 5 has effectively neutralized prompt injection attacks.
Deleting 80 Percent of System Promptsstrategy
The engineering team deleted over 80 percent of the system prompt for Claude Code because the new model is intelligent enough to execute tasks without legacy correction prompts.
Constant Evals Over Static Codebasesinsight
While codebases and system prompts should be routinely deleted and rebuilt with every new model generation, evaluation sets are kept and appended to until they are completely maxed out.
Rewriting Bun from Zig to Ruststory
Using a dynamic workflow with Claude Code, an engineer had the model rewrite the entire Bun JavaScript runtime codebase from Zig to Rust over an 11-day period.
Two-Week Autonomous GUI Rewritestory
The guest launched an ongoing experiment where Claude runs in a Mac virtual machine, rewrites the Electron desktop app in Swift, compares screenshots pixel-by-pixel, and updates a Slack channel every few minutes.
Automating Codebase Maintenance Routinesstrategy
Claude maintains its own codebases across CLI, iOS, Android, and desktop apps by running daily routines that clean up dead code, unify duplicate abstractions, and ship experiments.
“It has these skills, it has abilities that you actually didn't really teach it, but it just kind of learned.”
“The model does not seem to be prompt injectable anymore.”
“We deleted 80% of the system prompt.”
“And the verification, I think, is probably the single most important thing that people do not get right virtually.”
Fresh off the launch of Opus 5, Claude Code creator Boris Cherny joins Diana Hu at Startup School 2026 to talk about what the newest models can do, how Claude Code came to be, and what it means to build products when the underlying capabilities keep accelerating.
6,660 words · 2 speakers
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